Some generators, including those used with commercial aircraft, are required by design to disconnect from power transferred from a gearbox or other power transfer mechanism in the event of generator failure. Disconnecting the generator is a safety precaution to reduce the likelihood that a broken generator would damage the gearbox or engine and to reduce further damage to the generator. Some generators effectively use a yoke having a ramp to disconnect the generator from the gearbox. A yoke requires axial space to disconnect a gear shaft from a generator axle.
Modern variable frequency aircraft generators typically utilize axially preloaded angular contact bearings in order to increase the generator critical speed. This preload spring has traditionally been a crest-to-crest wave spring that is placed within a generator casing.
Reduction of the weight of aircraft parts to increase the efficiency of aircraft is a normal goal of aircraft part designers.